Merge pull request #9 from nden/refactor-and-tests

restructure and add stwcs tests

1 files changed, 758 insertions, 0 deletions

diff --git a/stwcs/wcsutil/altwcs.py b/stwcs/wcsutil/altwcs.py
new file mode 100644
index 0000000..aae1a9f
--- /dev/null
+++ b/stwcs/wcsutil/altwcs.py
@@ -0,0 +1,758 @@
+from __future__ import division, print_function # confidence high
+import os
+import string
+
+import numpy as np
+from astropy import wcs as pywcs
+from astropy.io import fits
+from stsci.tools import fileutil as fu
+
+altwcskw = ['WCSAXES', 'CRVAL', 'CRPIX', 'PC', 'CDELT', 'CD', 'CTYPE', 'CUNIT',
+            'PV', 'PS']
+altwcskw_extra = ['LATPOLE','LONPOLE','RESTWAV','RESTFRQ']
+
+# file operations
+def archiveWCS(fname, ext, wcskey=" ", wcsname=" ", reusekey=False):
+    """
+    Copy the primary WCS to the header as an alternate WCS
+    with wcskey and name WCSNAME. It loops over all extensions in 'ext'
+
+    Parameters
+    ----------
+    fname :  string or `astropy.io.fits.HDUList`
+        file name or a file object
+    ext :    int, tuple, str, or list of integers or tuples (e.g.('sci',1))
+        fits extensions to work with
+        If a string is provided, it should specify the EXTNAME of extensions
+        with WCSs to be archived
+    wcskey : string "A"-"Z" or " "
+        if " ": get next available key if wcsname is also " " or try
+        to get a key from WCSNAME value
+    wcsname : string
+        Name of alternate WCS description
+    reusekey : boolean
+        if True - overwrites a WCS with the same key
+
+    Examples
+    --------
+    Copy the primary WCS of an in memory headrlet object to an
+    alternate WCS with key 'T'
+
+    >>> hlet=headerlet.createHeaderlet('junk.fits', 'hdr1.fits')
+    >>> altwcs.wcskeys(hlet[1].header)
+    ['A']
+    >>> altwcs.archiveWCS(hlet, ext=[('SIPWCS',1),('SIPWCS',2)], wcskey='T')
+    >>> altwcs.wcskeys(hlet[1].header)
+    ['A', 'T']
+
+
+    See Also
+    --------
+    wcsutil.restoreWCS: Copy an alternate WCS to the primary WCS
+
+    """
+
+    if isinstance(fname, str):
+        f = fits.open(fname, mode='update')
+    else:
+        f = fname
+
+    if not _parpasscheck(f, ext, wcskey, wcsname):
+        closefobj(fname, f)
+        raise ValueError("Input parameters problem")
+
+    # Interpret input 'ext' value to get list of extensions to process
+    ext = _buildExtlist(f, ext)
+
+    if not wcskey and not wcsname:
+        raise KeyError("Either wcskey or wcsname should be specified")
+
+    if wcsname.strip() == "":
+        try:
+            wcsname = readAltWCS(f, ext[0], wcskey=" ")['WCSNAME']
+        except KeyError:
+            pass
+    wcsext = ext[0]
+    if wcskey != " " and wcskey in wcskeys(f[wcsext].header) and not reusekey:
+        closefobj(fname, f)
+        raise KeyError("Wcskey %s is aready used. \
+        Run archiveWCS() with reusekey=True to overwrite this alternate WCS. \
+        Alternatively choose another wcskey with altwcs.available_wcskeys()." %wcskey)
+    elif wcskey == " ":
+        # wcsname exists, overwrite it if reuse is True or get the next key
+        if wcsname.strip() in wcsnames(f[wcsext].header).values():
+            if reusekey:
+                # try getting the key from an existing WCS with WCSNAME
+                wkey = getKeyFromName(f[wcsext].header, wcsname)
+                wname = wcsname
+                if wkey == ' ':
+                    wkey = next_wcskey(f[wcsext].header)
+                elif wkey is None:
+                    closefobj(fname, f)
+                    raise KeyError("Could not get a valid wcskey from wcsname %s" %wcsname)
+            else:
+                closefobj(fname, f)
+                raise KeyError("Wcsname %s is aready used. \
+                Run archiveWCS() with reusekey=True to overwrite this alternate WCS. \
+                Alternatively choose another wcskey with altwcs.available_wcskeys() or\
+                choose another wcsname." %wcsname)
+        else:
+            wkey = next_wcskey(f[wcsext].header)
+            if wcsname.strip():
+                wname = wcsname
+            else:
+                # determine which WCSNAME needs to be replicated in archived WCS
+                wnames = wcsnames(f[wcsext].header)
+                if 'O' in wnames: del wnames['O'] # we don't want OPUS/original
+                if len(wnames) > 0:
+                    if ' ' in wnames:
+                        wname = wnames[' ']
+                    else:
+                        akeys = string.uppercase
+                        wname = "DEFAULT"
+                        for key in akeys[-1::]:
+                            if key in wnames:
+                                wname = wnames
+                                break
+                else:
+                    wname = "DEFAULT"
+    else:
+        wkey = wcskey
+        wname = wcsname
+
+    for e in ext:
+        hwcs = readAltWCS(f,e,wcskey=' ')
+        if hwcs is None:
+            continue
+
+        wcsnamekey = 'WCSNAME' + wkey
+        f[e].header[wcsnamekey] = wname
+
+        try:
+            old_wcsname=hwcs.pop('WCSNAME')
+        except:
+            pass
+        
+        for k in hwcs.keys():
+            key = k[:7] + wkey
+            f[e].header[key] = hwcs[k]
+    closefobj(fname, f)
+
+def restore_from_to(f, fromext=None, toext=None, wcskey=" ", wcsname=" "):
+    """
+    Copy an alternate WCS from one extension as a primary WCS of another extension
+
+    Reads in a WCS defined with wcskey and saves it as the primary WCS.
+    Goes sequentially through the list of extensions in ext.
+    Alternatively uses 'fromext' and 'toext'.
+
+
+    Parameters
+    ----------
+    f:       string or `astropy.io.fits.HDUList`
+             a file name or a file object
+    fromext: string
+             extname from which to read in the alternate WCS, for example 'SCI'
+    toext:   string or python list
+             extname or a list of extnames to which the WCS will be copied as
+             primary, for example ['SCI', 'ERR', 'DQ']
+    wcskey:  a charater
+             "A"-"Z" - Used for one of 26 alternate WCS definitions.
+             or " " - find a key from WCSNAMe value
+    wcsname: string (optional)
+             if given and wcskey is " ", will try to restore by WCSNAME value
+
+    See Also
+    --------
+    archiveWCS - copy the primary WCS as an alternate WCS
+    restoreWCS - Copy a WCS with key "WCSKEY" to the primary WCS
+
+    """
+    if isinstance(f, str):
+        fobj = fits.open(f, mode='update')
+    else:
+        fobj = f
+
+    if not _parpasscheck(fobj, ext=None, wcskey=wcskey, fromext=fromext, toext=toext):
+        closefobj(f, fobj)
+        raise ValueError("Input parameters problem")
+
+    # Interpret input 'ext' value to get list of extensions to process
+    #ext = _buildExtlist(fobj, ext)
+
+    if isinstance(toext, str):
+        toext = [toext]
+
+    # the case of an HDUList object in memory without an associated file
+
+    #if fobj.filename() is not None:
+    #        name = fobj.filename()
+
+    simplefits = fu.isFits(fobj)[1] is 'simple'
+    if simplefits:
+        wcskeyext = 0
+    else:
+        wcskeyext = 1
+
+    if wcskey == " ":
+        if wcsname.strip():
+            wkey = getKeyFromName(fobj[wcskeyext].header, wcsname)
+            if not wkey:
+                closefobj(f, fobj)
+                raise KeyError("Could not get a key from wcsname %s ." % wcsname)
+    else:
+        if wcskey not in wcskeys(fobj, ext=wcskeyext):
+            print("Could not find alternate WCS with key %s in this file" % wcskey)
+            closefobj(f, fobj)
+            return
+        wkey = wcskey
+
+    countext = fu.countExtn(fobj, fromext)
+    if not countext:
+        raise KeyError("File does not have extension with extname %s", fromext)
+    else:
+        for i in range(1, countext+1):
+            for toe in toext:
+                _restore(fobj, fromextnum=i, fromextnam=fromext, toextnum=i, toextnam=toe, ukey=wkey)
+
+    if fobj.filename() is not None:
+        #fobj.writeto(name)
+        closefobj(f, fobj)
+
+def restoreWCS(f, ext, wcskey=" ", wcsname=" "):
+    """
+    Copy a WCS with key "WCSKEY" to the primary WCS
+
+    Reads in a WCS defined with wcskey and saves it as the primary WCS.
+    Goes sequentially through the list of extensions in ext.
+    Alternatively uses 'fromext' and 'toext'.
+
+
+    Parameters
+    ----------
+    f : str or `astropy.io.fits.HDUList`
+        file name or a file object
+    ext : int, tuple, str, or list of integers or tuples (e.g.('sci',1))
+        fits extensions to work with
+        If a string is provided, it should specify the EXTNAME of extensions
+        with WCSs to be archived
+    wcskey : str
+        "A"-"Z" - Used for one of 26 alternate WCS definitions.
+        or " " - find a key from WCSNAMe value
+    wcsname : str
+        (optional) if given and wcskey is " ", will try to restore by WCSNAME value
+
+    See Also
+    --------
+    archiveWCS - copy the primary WCS as an alternate WCS
+    restore_from_to
+
+    """
+    if isinstance(f, str):
+        fobj = fits.open(f, mode='update')
+    else:
+        fobj = f
+
+    if not _parpasscheck(fobj, ext=ext, wcskey=wcskey):
+        closefobj(f, fobj)
+        raise ValueError("Input parameters problem")
+
+    # Interpret input 'ext' value to get list of extensions to process
+    ext = _buildExtlist(fobj, ext)
+
+
+    # the case of an HDUList object in memory without an associated file
+
+    #if fobj.filename() is not None:
+    #        name = fobj.filename()
+
+    simplefits = fu.isFits(fobj)[1] is 'simple'
+    if simplefits:
+        wcskeyext = 0
+    else:
+        wcskeyext = 1
+
+    if wcskey == " ":
+        if wcsname.strip():
+            wkey = getKeyFromName(fobj[wcskeyext].header, wcsname)
+            if not wkey:
+                closefobj(f, fobj)
+                raise KeyError("Could not get a key from wcsname %s ." % wcsname)
+    else:
+        if wcskey not in wcskeys(fobj, ext=wcskeyext):
+            #print "Could not find alternate WCS with key %s in this file" % wcskey
+            closefobj(f, fobj)
+            return
+        wkey = wcskey
+
+    for e in ext:
+        _restore(fobj, wkey, fromextnum=e, verbose=False)
+
+    if fobj.filename() is not None:
+        #fobj.writeto(name)
+        closefobj(f, fobj)
+
+def deleteWCS(fname, ext, wcskey=" ", wcsname=" "):
+    """
+    Delete an alternate WCS defined with wcskey.
+    If wcskey is " " try to get a key from WCSNAME.
+
+    Parameters
+    ----------
+    fname : str or a `astropy.io.fits.HDUList`
+    ext : int, tuple, str, or list of integers or tuples (e.g.('sci',1))
+        fits extensions to work with
+        If a string is provided, it should specify the EXTNAME of extensions
+        with WCSs to be archived
+    wcskey : str
+        one of 'A'-'Z' or " "
+    wcsname : str
+        Name of alternate WCS description
+    """
+    if isinstance(fname, str):
+        fobj = fits.open(fname, mode='update')
+    else:
+        fobj = fname
+
+    if not _parpasscheck(fobj, ext, wcskey, wcsname):
+        closefobj(fname, fobj)
+        raise ValueError("Input parameters problem")
+
+    # Interpret input 'ext' value to get list of extensions to process
+    ext = _buildExtlist(fobj, ext)
+    # Do not allow deleting the original WCS.
+    if wcskey == 'O':
+        print("Wcskey 'O' is reserved for the original WCS and should not be deleted.")
+        closefobj(fname, fobj)
+        return
+
+    wcskeyext = ext[0]
+
+    if not wcskeys and not wcsname:
+        raise KeyError("Either wcskey or wcsname should be specified")
+
+    if wcskey == " ":
+        # try getting the key from WCSNAME
+        wkey = getKeyFromName(fobj[wcskeyext].header, wcsname)
+        if not wkey:
+            closefobj(fname, fobj)
+            raise KeyError("Could not get a key: wcsname '%s' not found in header." % wcsname)
+    else:
+        if wcskey not in wcskeys(fobj[wcskeyext].header):
+            closefobj(fname, fobj)
+            raise KeyError("Could not find alternate WCS with key %s in this file" % wcskey)
+        wkey = wcskey
+
+    prexts = []
+    for i in ext:
+        hdr = fobj[i].header
+        hwcs = readAltWCS(fobj,i,wcskey=wkey)
+        if hwcs is None:
+            continue
+        for k in hwcs[::-1]:
+            del hdr[k]
+            #del hdr['ORIENT'+wkey]
+        prexts.append(i)
+    if prexts != []:
+        print('Deleted all instances of WCS with key %s in extensions' % wkey, prexts)
+    else:
+        print("Did not find WCS with key %s in any of the extensions" % wkey)
+    closefobj(fname, fobj)
+
+def _buildExtlist(fobj, ext):
+    """
+    Utility function to interpret the provided value of 'ext' and return a list
+    of 'valid' values which can then be used by the rest of the functions in
+    this module.
+
+    Parameters
+    ----------
+    fobj: HDUList
+        file to be examined
+    ext:    an int, a tuple, string, list of integers or tuples (e.g.('sci',1))
+            fits extensions to work with
+            If a string is provided, it should specify the EXTNAME of extensions
+            with WCSs to be archived
+    """
+    if not isinstance(ext,list):
+        if isinstance(ext,str):
+            extstr = ext
+            ext = []
+            for extn in range(1, len(fobj)):
+                if 'extname' in fobj[extn].header and fobj[extn].header['extname'] == extstr:
+                    ext.append(extn)
+        elif isinstance(ext, int) or isinstance(ext, tuple):
+            ext = [ext]
+        else:
+            raise KeyError("Valid extensions in 'ext' parameter need to be specified.")
+    return ext
+
+def _restore(fobj, ukey, fromextnum,
+             toextnum=None, fromextnam=None, toextnam=None, verbose=True):
+    """
+    fobj: string of HDUList
+    ukey: string 'A'-'Z'
+          wcs key
+    fromextnum: int
+                extver of extension from which to copy WCS
+    fromextnam: string
+                extname of extension from which to copy WCS
+    toextnum: int
+              extver of extension to which to copy WCS
+    toextnam: string
+              extname of extension to which to copy WCS
+    """
+    # create an extension tuple, e.g. ('SCI', 2)
+    if fromextnam:
+        fromextension = (fromextnam, fromextnum)
+    else:
+        fromextension = fromextnum
+    if toextnum:
+        if toextnam:
+            toextension = (toextnam, toextnum)
+        else:
+            toextension =toextnum
+    else:
+        toextension = fromextension
+
+    hwcs = readAltWCS(fobj,fromextension,wcskey=ukey,verbose=verbose)
+    if hwcs is None:
+        return
+
+    for k in hwcs.keys():
+        key = k[:-1]
+        if key in fobj[toextension].header:
+            #fobj[toextension].header.update(key=key, value = hwcs[k])
+            fobj[toextension].header[key] = hwcs[k]
+        else:
+            continue
+    if key == 'O' and 'TDDALPHA' in fobj[toextension].header:
+        fobj[toextension].header['TDDALPHA'] = 0.0
+        fobj[toextension].header['TDDBETA'] = 0.0
+    if 'ORIENTAT' in fobj[toextension].header:
+        norient = np.rad2deg(np.arctan2(hwcs['CD1_2'+'%s' %ukey], hwcs['CD2_2'+'%s' %ukey]))
+        fobj[toextension].header['ORIENTAT'] = norient
+    # Reset 2014 TDD keywords prior to computing new values (if any are computed)
+    for kw in ['TDD_CYA','TDD_CYB','TDD_CXA','TDD_CXB']:
+        if kw in fobj[toextension].header:
+            fobj[toextension].header[kw] = 0.0
+
+#header operations
+def _check_headerpars(fobj, ext):
+    if not isinstance(fobj, fits.Header) and not isinstance(fobj, fits.HDUList) \
+                   and not isinstance(fobj, str):
+        raise ValueError("Expected a file name, a file object or a header\n")
+
+    if not isinstance(fobj, fits.Header):
+        #raise ValueError("Expected a valid ext parameter when input is a file")
+        if not isinstance(ext, int) and not isinstance(ext, tuple):
+            raise ValueError("Expected ext to be a number or a tuple, e.g. ('SCI', 1)\n")
+
+def _getheader(fobj, ext):
+    if isinstance(fobj, str):
+        hdr = fits.getheader(fobj,ext)
+    elif isinstance(fobj, fits.Header):
+        hdr = fobj
+    else:
+        hdr = fobj[ext].header
+    return hdr
+
+def readAltWCS(fobj, ext, wcskey=' ',verbose=False):
+    """ Reads in alternate WCS from specified extension
+
+    Parameters
+    ----------
+    fobj : str, `astropy.io.fits.HDUList`
+        fits filename or fits file object
+        containing alternate/primary WCS(s) to be converted
+    wcskey : str
+        [" ",A-Z]
+        alternate/primary WCS key that will be replaced by the new key
+    ext : int
+        fits extension number
+
+    Returns
+    -------
+    hdr: fits.Header
+        header object with ONLY the keywords for specified alternate WCS
+    """
+    if isinstance(fobj, str):
+        fobj = fits.open(fobj)
+
+    hdr = _getheader(fobj,ext)
+    try:
+        nwcs = pywcs.WCS(hdr, fobj=fobj, key=wcskey)
+    except KeyError:
+        if verbose:
+            print('readAltWCS: Could not read WCS with key %s' %wcskey)
+            print('            Skipping %s[%s]' % (fobj.filename(), str(ext)))
+        return None
+    hwcs = nwcs.to_header()
+
+    if nwcs.wcs.has_cd():
+        hwcs = pc2cd(hwcs, key=wcskey)
+
+    return hwcs
+
+def convertAltWCS(fobj,ext,oldkey=" ",newkey=' '):
+    """
+    Translates the alternate/primary WCS with one key to an alternate/primary WCS with
+    another key.
+
+    Parameters
+    ----------
+    fobj : str, `astropy.io.fits.HDUList`, or `astropy.io.fits.Header`
+        fits filename, fits file object or fits header
+        containing alternate/primary WCS(s) to be converted
+    ext : int
+        extension number
+    oldkey : str
+        [" ",A-Z]
+        alternate/primary WCS key that will be replaced by the new key
+    newkey : str
+        [" ",A-Z]
+        new alternate/primary WCS key
+
+    Returns
+    -------
+    hdr: `astropy.io.fits.Header`
+        header object with keywords renamed from oldkey to newkey
+    """
+    hdr = readAltWCS(fobj,ext,wcskey=oldkey)
+    if hdr is None:
+        return None
+    # Converting WCS to new key
+    for card in hdr:
+        if oldkey == ' ' or oldkey == '':
+            cname = card
+        else:
+            cname = card.rstrip(oldkey)
+        hdr.rename_key(card,cname+newkey,force=True)
+
+    return hdr
+
+def wcskeys(fobj, ext=None):
+    """
+    Returns a list of characters used in the header for alternate
+    WCS description with WCSNAME keyword
+
+    Parameters
+    ----------
+    fobj : str, `astropy.io.fits.HDUList` or `astropy.io.fits.Header`
+          fits file name, fits file object or fits header
+    ext : int or None
+         extension number
+         if None, fobj must be a header
+    """
+    _check_headerpars(fobj, ext)
+    hdr = _getheader(fobj, ext)
+    names = hdr["WCSNAME*"]
+    d = []
+    for key in names:
+        wkey = key.replace('WCSNAME','')
+        if wkey == '': wkey = ' '
+        d.append(wkey)
+    return d
+
+def wcsnames(fobj, ext=None):
+    """
+    Returns a dictionary of wcskey: WCSNAME pairs
+
+    Parameters
+    ----------
+    fobj : stri, `astropy.io.fits.HDUList` or `astropy.io.fits.Header`
+          fits file name, fits file object or fits header
+    ext : int or None
+         extension number
+         if None, fobj must be a header
+
+    """
+    _check_headerpars(fobj, ext)
+    hdr = _getheader(fobj, ext)
+    names = hdr["WCSNAME*"]
+    d = {}
+    for keyword, value in names.items():
+        wkey = keyword.replace('WCSNAME','')
+        if wkey == '': wkey = ' '
+        d[wkey] = value
+    return d
+
+def available_wcskeys(fobj, ext=None):
+    """
+    Returns a list of characters which are not used in the header
+    with WCSNAME keyword. Any of them can be used to save a new
+    WCS.
+
+    Parameters
+    ----------
+    fobj : str, `astropy.io.fits.HDUList` or `astropy.io.fits.Header`
+        fits file name, fits file object or fits header
+    ext : int or None
+        extension number
+        if None, fobj must be a header
+    """
+    _check_headerpars(fobj, ext)
+    hdr = _getheader(fobj, ext)
+    all_keys = list(string.ascii_uppercase)
+    used_keys = wcskeys(hdr)
+    try:
+        used_keys.remove(" ")
+    except ValueError:
+        pass
+    [all_keys.remove(key) for key in used_keys]
+    return all_keys
+
+def next_wcskey(fobj, ext=None):
+    """
+    Returns next available character to be used for an alternate WCS
+
+    Parameters
+    ----------
+    fobj : str, `astropy.io.fits.HDUList` or `astropy.io.fits.Header`
+        fits file name, fits file object or fits header
+    ext : int or None
+        extension number
+        if None, fobj must be a header
+    """
+    _check_headerpars(fobj, ext)
+    hdr = _getheader(fobj, ext)
+    allkeys = available_wcskeys(hdr)
+    if allkeys != []:
+        return allkeys[0]
+    else:
+        return None
+
+def getKeyFromName(header, wcsname):
+    """
+    If WCSNAME is found in header, return its key, else return
+    None. This is used to update an alternate WCS
+    repeatedly and not generate new keys every time.
+
+    Parameters
+    ----------
+    header :  `astropy.io.fits.Header`
+    wcsname : str
+        value of WCSNAME
+    """
+    wkey = None
+    names = wcsnames(header)
+    wkeys = []
+    for item in names.items():
+        if item[1].lower() == wcsname.lower():
+            wkeys.append(item[0])
+    wkeys.sort()
+    if len(wkeys) > 0:
+        wkey = wkeys[-1]
+    else:
+        wkey = None
+    return wkey
+
+def pc2cd(hdr, key=' '):
+    """
+    Convert a CD PC matrix to a CD matrix.
+
+    WCSLIB (and PyWCS) recognizes CD keywords as input
+    but converts them and works internally with the PC matrix.
+    to_header() returns the PC matrix even if the i nput was a
+    CD matrix. To keep input and output consistent we check
+    for has_cd and convert the PC back to CD.
+
+    Parameters
+    ----------
+    hdr: `astropy.io.fits.Header`
+
+    """
+    for c in ['1_1', '1_2', '2_1', '2_2']:
+        try:
+            val = hdr['PC'+c+'%s' % key]
+            del hdr['PC'+c+ '%s' % key]
+        except KeyError:
+            if c=='1_1' or c == '2_2':
+                val = 1.
+            else:
+                val = 0.
+        #hdr.update(key='CD'+c+'%s' %key, value=val)
+        hdr['CD{0}{1}'.format(c, key)] = val
+    return hdr
+
+def _parpasscheck(fobj, ext, wcskey, fromext=None, toext=None, reusekey=False):
+    """
+    Check input parameters to altwcs functions
+
+    fobj : str or `astropy.io.fits.HDUList` object
+        a file name or a file object
+    ext : int, a tuple, a python list of integers or a python list
+        of tuples (e.g.('sci',1))
+        fits extensions to work with
+    wcskey : str
+        "A"-"Z" or " "- Used for one of 26 alternate WCS definitions
+    wcsname : str
+        (optional)
+        if given and wcskey is " ", will try to restore by WCSNAME value
+    reusekey : bool
+        A flag which indicates whether to reuse a wcskey in the header
+    """
+    if not isinstance(fobj, fits.HDUList):
+        print("First parameter must be a fits file object or a file name.")
+        return False
+
+    # first one covers the case of an object created in memory
+    # (e.g. headerlet) for which fileinfo returns None
+    if fobj.fileinfo(0) is None:
+        pass
+    else:
+        # an HDUList object with associated file
+        if fobj.fileinfo(0)['filemode'] is not 'update':
+            print("First parameter must be a file name or a file object opened in 'update' mode.")
+            return False
+
+    if not isinstance(ext, int) and not isinstance(ext, tuple) \
+        and not isinstance(ext,str) \
+        and not isinstance(ext, list) and ext is not None:
+        print("Ext must be integer, tuple, string,a list of int extension numbers, \n\
+        or a list of tuples representing a fits extension, for example ('sci', 1).")
+        return False
+
+    if not isinstance(fromext, str) and fromext is not None:
+        print("fromext must be a string representing a valid extname")
+        return False
+
+    if not isinstance(toext, list) and not isinstance(toext, str) and \
+                     toext is not None :
+        print("toext must be a string or a list of strings representing extname")
+        return False
+
+    if len(wcskey) != 1:
+        print('Parameter wcskey must be a character - one of "A"-"Z" or " "')
+        return False
+
+    return True
+
+def closefobj(fname, f):
+    """
+    Functions in this module accept as input a file name or a file object.
+    If the input was a file name (string) we close the object. If the user
+    passed a file object we leave it to the user to close it.
+    """
+    if isinstance(fname, str):
+        f.close()
+
+def mapFitsExt2HDUListInd(fname, extname):
+    """
+    Map FITS extensions with 'EXTNAME' to HDUList indexes.
+    """
+
+    if not isinstance(fname, fits.HDUList):
+        f = fits.open(fname)
+        close_file = True
+    else:
+        f = fname
+        close_file = False
+    d = {}
+    for hdu in f:
+        if 'EXTNAME' in hdu.header and hdu.header['EXTNAME'] == extname:
+            extver = hdu.header['EXTVER']
+            d[(extname, extver)] = f.index_of((extname, extver))
+    if close_file:
+        f.close()
+    return d